peters



UNITED STATES PATENT OFFICE.

ISAIAH ROGERS, OF NEXV YORK, N. Y.

MANNER OF CONSTRUCTING BRIDGES OF WOOD OR IRON, DENOMINATED THESEIRAL-BRACED CYLINDER-BRIDGE.

Specification of Letters Patent No.

To @ZZ whom t may concern.'

Be it known that I, IsAmH ROGERS, architect, of the city of New York, inthe State of New York, have invented a new and Improved Method or Systemof Constructing Bridges, Either of Nood or of Iron; and I do herebydeclare that the following is a full and exact description thereof.

I denominate my bridge, the spiral-braced cylinder bridge, the materialswhether of wood or of iron, of which its exterior framework is composed,being so put together', as to constitute a complete latticed cylinder,from end to end, the lattices being formed by spiral braces, surroundingthe cylinders. lVithin this cylinder, and along its whole extent Iconstruct a hollow rectangular prism, which is to constitute thepassageway of the bridge, this prism is formed by the flooring, byvertical sides, and by horizontal cross-ties uniting the vertical sidesat their upper edges. The vertical sides I form of a series of rings, orcircles, united together, and to vertical studs and horizontalstringpieces, by means of bolts or other adequate fastenings havingcross-ties above and below, these forming together a continuous trussbracing, which materially increases the strength of the cylindricalskeleton of the bridge. In bridges of a long span, the roadway is to bedvided into two parts, by a central partition construct-ed in allrespects in a manner similar to that of the vertical sides. The skeletonof my cylinder' bridge consists of circular ribs and stringpieces,strongly united together, by or combined with diagonal braces saidbraces dividing the whole exterior into diamond formed latticed work.These diagonal braces are in wooden-bridges, constructed of twothicknesses of plank, strongly bolted together, the pieces breakingjointing with each other, the respective diagonal braces form continuousspi al lines from end to end of the bridge, said spiral brace piecesrunning in reverse directions and constituting a trussing by which thestrain or weight is equally distributed over the whole structure. Inwooden bridges built upon this principle it is not necessary to use anyother timber than plank of from two to three inches in thickness. Inbridges of a short span boards of an inch or an inch and a quarter inthickness will afford suiii'cient strength when properly put together.At their intersec- 2,347, dated November 10, 1841.

tions the circles, braces and string pieces are to be bolted, riveted,screwed or nailed together, and the whole frame is intended to be formedwithout halving the timbers and without the use of mortises and tenons.In bridges of iron the bars of which the ribs and string pieces areformed may be four, tive or six inches wide, from one halt tothree-fourths of an inch in thickness; and in forming the circular ribsthese bars are to be bent edgewise. In bridges of this construction asthere is not any lateral thrust upon the piers or abutments, they may belaid in stone masonry, or be formed of a structure of timber framed orpiles or mudsills. When a bridge of this kind is to have a span ofunusual length one or more arched tubes may be constructed upon t-hesame principle with that of the cylinder of the bridge; which archedtube is to be placed below the cylindrical bridge, its ends bearingagainst suitable abutments, and its crown, or upper part, coming intoContact with the center of the bridge on its lower side.

In the accompanying drawings Figure 1 is a cross section of acylindrical bridge, ot' wood, with t-he rectangular prism therein,constituting the passage way. Fig. 2 is a longitudinal section thereofsho-wing the manner of constructing one of the vert-ical sides. Fig. 3is a sectional porton of a wooden bridge, showing the ribs and stringpieces, with the spiral cross bracing surrounding them. Fig. 8 is asection oi the ribs and string pieces o-n an enlarged scale showing themanner of joining them together. Fig. 9 a part of the longitudinalsection of the vertical side shown in Fig. 2 drawn also on an enlargedscale, for the purpose of exhibiting the manner of combining therespective parts with each other. Fig. 10 is a plan of the flooring of abridge with a single carriage way, which flooring will not differmaterially whether applied to a bridge of wood or of iron. Fig. 7 is aside elevation of a cylindrical bridge of a long span, sustained at itscenter by a tubular arch PP, bearing against suitable abutments. Fig. 4fis a cross section of an iron bridge, showing a double roadway; in thisarrangement the sides of the roadway are not vertical, this not being anessential feature, more especially in bridges of iron. Fig. 5 is alongitudinal section of an iron bridge showing a vertical elevation ofthe braced division between the two roadways in Fig. 4. Fig. 6 is asectional portion of an iron bridge, with its ribs, string pieces, andbraces combined together, on the saine principle with those of thewooden bridge as shown in Fig. 3. Fig. l1 is a sectional view of a partof the iron ribs and string pieces, showing on an enlarged scale themanner in which they may be joined together.

In Fig. 3, A., A, are two of the ribs, and B, B, one of the stringpieces, a number of each being shown in the same iigure, as they areembraced by the diagonal braces, a, a, a; each of these braces passingin a co-ntinued spiral from end to end of the bridge. In Fig. 8 A, A,are portions of two of the circular ribs, made of two thicknesses ofplank, breaking joints with each other, and bolted together, and to thestring pieces B, B, B. rlhese string pie-ces connect, like the ribs, oftwo pieces of plank united to each other and to the ribs, as abovenamed. In the cross section, Fig. l, A, A, is one of the circular ribs,and a ,ct, a, the diagonal braces; the string pieces being shown intheir cross section, between them. In the longitudinal section Fig. 2,showing one of the vertical sides of the roadway, and in the enlargedview of a portion of this section, Fig. 9, F, F, are rings, or circles,consisting of two thicknesses ot plank, bolted together as at b, b, andthese rings bolted to each other and to studs G, Gr, as at C, C, and tostring pieces H, H, as at (Z, CZ. I and J are the upper and lowerlstring pieces, from which proceed the horizontal cross ties K, L.

In this bridge, when formed of iron the ribs and string pieces are madeof single and continuous bars. In Fig. G, E, is one of the ribs, and D,one of the string pieces, a number of each being shown in the sameiigure; and e, e, are the diagonal braces, surrounding the whole, in thesame manner with those shown at a, a, in the wooden bridge. In Fig. 4l,E, is one of the ribs;e, c,

#the diagonal braces, the cross sections of the string pieces beingshown between them. M, M, are two segments of rings riveted to E, and tocross ties N, O, and united also to suitable brace pieces which may bevariously arranged.

In Fig. 11, E, E, are segments of two of the ribs, showing the bars ofiron of which they are formed as bent edgewise. D, D, are sections oftwo of the string pieces. The ribs and string pieces are shown asfastened together in two different modes; the manner of doing this maybe varied according to the judgment of the engineer.

In the longitudinal section, Fig. 5, showing the vertical partition, thearrangement of the hoops, string pieces, and brace pieces which enterinto its composition, will be clearly understood from an inspection ofthe drawing, and need not be specially described; nor is it intended tolimit the arrangement of these parts to the particular mode thereinrepresented. The bridge so constructed may be covered, or inclosed,either in whole or in part, by a case or roof, of wood, or of metal; thebest arrangement in this particular is believed to be the inclosing by acontinuous covering of the upper half of the cylinder of which it iscomposed.

Having thus fully described the nature of my invention, and shown themanner in which the same may be carried into operation; what I claimtherein as new and desire to secure by Letters Patent, is-

The constructing of a cylindrical bridge, either of wood, or of iron, bythe combining together of circular ribs, string pieces, and diagonalbraces, which braces consistof continuous strips of wood, or of iron,surrounding the ribs, and string pieces, and passing spirally, inreversed directions, from end to end of the bridge, thus constituting abraced lattice work, on the exterior of the cylinder. The whole beingconstructed, arranged, and combined, substantially in the manner hereinset forth. I also claim, in combination with such a cylindrical bridge,the forming of a hollow rectangular passage way, having its verticalsides, or a vertical partition, constructed, arranged, and combined,substantially as herein represented and made known.

ISAIAH ROGERS.

lVitnesses JOHN B. HOLMES, Ti-inononn Vonoknns.

